Textile fiber



Patented July 12, 1938 UNITED STATES PATENT OFFICE TEXTILE FIBER MartinEli Cupery, Wilmington, DeL, assignor to E]. du Pont de Nemours &Company, Wilmington, DeL, a corporation of Delaware No Drawing.

Application February s, 1936, SerialNo. 64,159

6 Claims. (01. 91- -es This invention is directed to the production 01"artificial textile fibers or filaments suitably coated, impregnated orotherwise treated with a material or materials adapted to impart to suchfibers or filaments improved softness, 'resiliency, toughness, strength,and solvent resistance characteristics.- r

In a more particular embodiment, the invention is directed to theproduction of artificial fibers or filaments adapted to be employed asartificial bristles, and advantageous substitutes for natural fibers,such as pig bristles, horsehair, or vegetable fibers. v

It has been customary, in prior practices, to produce artificial fibersor filaments byjcoating a suitable thread or filament with collodion orsimilar nitrated cellulose. Likewise, viscose and and varnish have beenemployed as coating agents for such threads or filaments. Similarly,

attempts have been made to produce" artificial fibers by coatingthreadsor filaments with solu-,

tions of cellulose acetate of the type which is soluble in methylacetate, acetone, etc.

The artificial textile fibers produced from such prior practices,however, are very unsatisfactory for use as natural bristle substitutesbecause they possess inherent deficiencies and disadvantages. Amongother things, they are whollyjunsuitable for use as artificial bristlessince'they aresusceptible to and influenced by the action of suchordinary solvents as water and organic solvents with which solvents theymay come in contact during use. These solvents effect an unduesoftening. or warping of the synthetic fibers, causing them to becomeunfit and useless for further employment. Moreover, in instances saryand requisite for artificial bristles whichare to. be satisfactorilyemployed in ordinary commercial uses.-

It is among the objects of the present invention, therefore, toovercomethe foregoing as well as other objections and disadvantagesexistent in the artificial fibers or filaments heretofore proofcommercial paint brushes will have especial adaptability, since suchtypes of brushes are duced, and to provide an improved artificial fiberor bristle which possesses, among other desirable properties, a highresistance to solvents, particularly hot or cold water, and to suchordinary organic solvents as alcohols, esters, etc.; an 5 equallyeffective resistance to hydrocarbon solj vents of the type employed inpaints and varnishes; improved resistance to animal, vegetable oils andfats; and improved resilience, toughness,

and tensile strength properties. Furthermore, it is also among theobjects of the present invention to provide a fiber element ofacharacter such that it closely resemblesbleached natural pig bristles.

The foregoing, as well as other, objects and 5 advantages of theinvention may be attained by treating, preferably, a variety offilaments or threads, such as multifilament rayon yarn (regeneratedcellulose yarn or cellulose acetate yarn), single filament viscoserayon. straw, artificial horsehair rayon, or cotton, silk, linen, ramie,or wool thread, with a solution or solutions which contain as anessential ingredient. or constituent cellulose triacetate alone ormixtures thereof with othermaterials. The term cellulose trlacetate" asemployed herein is intended to refer to the cellulose acetates whichcontain about 2.7 to about 3 acetyl groups per glucose unit, and arecharacterized by being insoluble in acetone and soluble only in certainalcohol-halogenated hy-= 30 drocarbon solvent mixtures, such. asmethylene chloride-methanol. In the employmentof cellulose triacetate asan ingredient of the coating or impregnating composition for the threador filament, it will be found that the resultant product will possessall the desired attributes heretofore referred to, including highwater-insensitivity, and increased resistance toward organic solvents,particularly the hydrocarbons, alcohols, esters, animal and vegetableoils and fats, etc, Having these properties, the resultant bristles,when fabricated into commercial articles, will obviously possessenhanced commercial utility, and in the instance constantly subjectedduring use to' deleterious attack by hydrocarbon solvents present in thepaint.

In producing the artificial fibers or bristles of the present invention,a single but preferablya-5 plurality of coatings of solutions containingcellulose triacetate as the essential ingredient, may be successivelyand independently applied to a thin, supporting baseor filament. Whilepreferably each coating application may con- 55 -tion with otherwell-known film-forming substances. If desired, however, the coatingstructure and application may also be varied to produce a compositeeffect whereby a plurality of film-forming coatings are applied to abase material, one of which coatings may comprise cellulose triacetatealone, cellulose triacetate in ad-- mixture with other film-formingsubstances, or a non-cellulose triacetate coating, all of which may bealternately and successively applied in any desired relationship to thebase material to produce the desired laminated effect. In the latterinstance, however, it is preferable, in view of the essential attributeswhich cellulose triacetate imparts to the resulting filament or bristle,that the cellulose triacetate coating comprise the outer or externalfilm in the laminated structure. a

In carrying the invention into effect, any wellknown method' and/orapparatus for applying the coating solutions to the thread or filamentmay be employed. For example, the filament may be initially drawn from aretaining spool into and through one or more solutions containingcellulose triacetate. Thereafter, the coated thread may be passedthrough an orifice nozzle, or similar means, ranging in diameter, forexample, from 0.2 to 1 mm., or higher as desired, adapted to scrape offand remove any excess coating from the thread, and maintain its diameteruniform throughout. Thereupon, the coated thread may be passed through aconventional drying tower or oven to remove volatile solvents present inthe coating composition, and after the drying operation, the coatedthread may again be passed through the same or a different coatingsolution of cellulose triacetate, as desired, and

the entire method repeated. After each application of coating, ofcourse, a proportionate indiameter must be employed, and this must becommensurate with and in conformity to the resultant desired increase inthe diameter of the coated thread. The coating operation may be repeatedany number of times, whereby coated filaments of any desired diameterand any number or plurality of coatings result.

Each of the successive and independently applied coating solutions ofcellulose triaceta'te may vary in percentage composition, making itpossible to vary the film thickness of the individually appliedcoatings. as desired. By suitable variations in either the concentrationof the coating solution, or its composition, it will obviously bepossible to produce fibers exhibiting widely varying characteristics.Additionally suitable pigments, colors, etc., may, if desired, beincorporated in one or all of the various coating compositions, effectsmay be produced. Furthermore, by proper regulation of the coatingcomposition and its method of application to the threads, fibers ofcontinuous length and of uniform size may be produced, and may be eithersubstantially circular, orin suitably shaped cross-section.

In order that the invention may be more fully understood, thefollowingspecific examples are given, each of which, it is understood, is to be aplurality of coatings of whereby many novel and useful taken in no wiselimiting, but as merely exemplifying the invention:-

Example 1 A 40 filament viscose rayon yarn of denier and having fourturns per inch was passed through a solution comprising 15% cellulosetriacetate, 3% plasticizer, 8% methanol, and 74% methylene chloride, inthe usual conventional manner. The excess coating solutionwasremoved bydrawing the coated thread through a small nozzle orifice. After passagethrough a drying chamber, which was maintained at 45-50" C., the coatedthread was subjected to repeated treatment with the same solution untilfour coatings had been applied thereto, the nozzle orifice during eachtreatment being, respectively, 0.3, 0.4, 0.5 and 0.6 mm. in diameter.The last coating solution also contains about 4% by weight of titaniumoxide based on the cellulose triacetate present. The thread was drawnthrough the several coating solutions at an approximate rate of 20 feetper minute, and the finished fiber collected on wood panels andsubsequently dried for /2 hour at 100 C., immersed in water at 50 C.,for 15 minutes, followed by a final drying at 100 C. for 3 hours. Thefibers were then removed from the panels and cut into the desiredlengths. The fibers thus obtained were 0.28 to 0.31 mm. in diameter; ofapproximately 900 denier, and had a substantially circular crosssection.They had a creamy, translucent, glossy white appearance which closelyresembled natural pig bristles. They showed practically no softening orwarping upon immersion in water at room temperature for 24 hours. Thesefibers did not break on bending sharply, showed good resiliency,toughness, and tensile strength, and hair brushes fabricated therefromcompared favorably in quality with similar brushes fabricated from highgrade natural bristles.

Example 2 Example 3 A 40 filament denier viscose rayon thread havingthree turns per inch was successively coated with the following fivecompositions in the order given, using nozzle orifices of the sizesdesignated for each application.

Coat #1.Cellulose triacetate 1 5%, plasticizer 3%, methanol 8%,methylene chloride 74%; nozzle orifice 0.27 mm. in diameter.

Coat #2.-l0-second nitrocellulose nitrogen) 21%, alcohol 16%, acetone63%; orifice 0.30 mm. in diameter.

Coat #3.Cellulose triacetate, same composition as No. 1 above, with 5%by weight titanium oxide added, based on cellulose acetate; nozzleorifice 0.35 mm. in diameter.

Coat #4.Nitrocellulose, composition same as No. 2 above; nozzle orifice0.40 mm. diameter.

Coat #5.-Cellulose triacetate, composition same as No. 1 above; nozzleorifice 0.50 mm. in diameter.

(1 1.9 nozzle uct was collected on wood panels, dried for one hour at100 'C., immersed in water at 60 C. for

15 minutes, dried at 100 C. for 1 hours, then at 65 C. for 16 hours, V

The product was removed from the wood panels by cutting the fiber at theend of the panels.

After the ends were trimmed off straight fibers ranging from 0.25 to0.31 mm. in diameter and having a nearly uniform circular cross-sectionwere obtained. Such fibers had a denier of approximately 800, and wereglossy white in appearance. Upon immersion in either cold or hot watersuch fibers showed practically no softening or warping. The resistancetoward softening in water heated at 90-100 C. was superior to that ofthe fibers produced by Example 1. These fibers. also showed improvedtoughness and resiliency, and were employed as bristles in thefabrication of clothes brushes and hair brushes with good results. r

. Example 4 than the products produced by Examples 1 and 3.

Example 5 A 40 filament viscose rayon thread of 150 denier and havingthree turns per inch was successively coated with the following fourcompositions in the order given, and using nozzle orifices of the sizedesignated for each application. v

Coat #1.-- Cel1ulose triacetate 15%, plasticizer 3%, methanol 8%,methylene chloride 74%; nozzle orifice 0.3 mm. diameter.

Coat s z -Methyl methacrylate polymer 15%, benzene 50%, ethyl alcoholmethylene chloride 25%, nozzle orifice 0.4 mm. diameter. 7

Coat #3.-10-second nitrocellulose (11.9% nitrogen) 21%, ethyl alcohol16%, acetone 53%;

nozzle orifice 0.45 mm. diameten Coat #4.--Cellulose triacetate,composition same as coating #1 with 3% by weight of titanium oxide,based on cellulose triacetate; added; nozzle orifice 050mm. diameter.

The .various coating compositions were maintained at 30 35 C; duringthe'process and the drying chamber was kept at 50-52" 0. The rayonthread was drawn through the cbating solution at a rate 'of about 38 ft.permln'ute. After collecting the finished fiber on wooden panels, theproduct was immersed in warm water and dried as described in Example 1.

The fibers obtained had a uniform circular cross-sectionof 01.23 to 0.25mm. diameter. and in appearance and properties resembled the fibersdescribed in Example 1. water the product showed practically no tendencyto warp.

Example 6 Artificial fibers were prepared according to the threadfollowing each application.

Upon immersion in procedure of Example 1 by using a coating compositioncomprising cellulose triacetate 16%, plasticizer 4%, methanol 8%,methylene chloride 72%, for each of the four coatings applied to a 40filament viscose rayon thread of 150v denier and having three turns perinch. The fibers obtained showed greater pliability than the fibersproduced by any of the foregoing examples. These fibers also showedimproved toughness and elasticity.

Example 7 Artificial fibers of about 900 denier were prepared accordingto Example 1 except that the last or fourth coating compositioncontained Example 8 Two, three, or four coatings of a solution comprising cellulose triacetate plasticizer (phthalic acid esters of themixed primary and secondary aliphatic branch chain alcohols containingfrom 6 to 15 carbon atoms, such alcohols as are obtained as a byproductin the hydrogenation of carbon oxides) 3%, carbon black pigment (welldispersed) 0.5%, methylene chloride 72.5%, methanol 9%, were applied to150 denier, 40 filament, 3 turns per inch viscose rayon thread which wasdrawn at a linear rate of 3'7 to 60 feet per minute. The drying chamberwas maintained at 60-70 C. Nozzle orifices having a diameter of 0.30,0.35, 0.40, 0.45 mm. were used in the order given for the application offour coatings, or the first two nozzle sizes listed for the applicationof two coatings, or the first three nozzle sizes listed for theapplication of three coatings of the above composition. -'I'he productswere collected and dried as in Example 1.

Fibers prepared by applying two coats of the above composition had adiameter of 0.20 mm. While fibers obtained by applying three coats wereabout 0.25 mm. in diameter, and the fibers having four coats were about0.30 mm. in diameter. All of the fibers were of substantially circularcross-section and showeda glossy, uniform black color, and closelyresembled natural horsehair in appearance, stilfness, resiliency, andtoughness. Paint brushes fabricated from such fibers showed no softeningin gasolinearomatic hydrocarbons, turpentine, or oils.

The foregoing description and examples define a process for thepreparation of artificial fibers which comprises applying to asupporting filament a plurality of coats from the same or differentcoating compositions and drying the coated It is obvious that thesupporting filament or thread is in general of less importancelndeveloping the required characteristics of an artificial fiber than thecoating material which is applied. Hence, a variety of filaments orthreads may be used without appreciably altering or atfecting thequality of the resultant fibers. For example, in addition to the typesof threads or filaments heretofore enumerated, small wires may alsobe'employed as'the supporting filament, and are especially suited forthe preparation of fibers or bristles where a high degree of toughnessor resiliency is requisite. s

In carrying out the invention it has been found preferable and desirablein all cases to avoid as far as possible any undue stretching of thesupporting filament during the coating operation. It has also been foundpreferable to employ coating solutions having a viscosity of from 15 to25 poises at 25 C. However, these conditions are not invariable for incertain modifications it will be found possible to employ solutions ofvaried concentrations having a viscosity range of -100 poises at 25 C.Again, it is advantageous, andtherefore preferable, to employ solventsor solvent mixtures having low-boiling characteristics, such as within arange of 40-70" 0., since these produce optimum results. It is to beunderstood, however, that higher boiling solvents may, if desired, beemployed, but these generally require resort to higher dryingtemperatures.

In most of the specific examples a warm water immersion treatment wasgiven the fibers. This serves to remove residual strains within thefibers so that the final product has little or no tendency to warp uponsubsequent prolonged immersion in water. The same results may, ifdesired, be accomplished by steaming the dried fibers or subjecting themto a high temperature for'a short period of time.

Again, in most of these examples no particular plasticizer for thecellulose triacetate has been specifically designated. It will be foundpreferable, however, to employ such plasticizers as the carbamates ofthe mixed branched chain primary and secondary aliphatic alcoholscontaining 6-15 carbon atoms (such alcohols as are obtained asby-products of the hydrogenation of carbon oxides). While these arepreferred, other plasticizers comprising'the phthalic acid esters ofsuch alcohols, diacetin or triacetin, camphor, beta-naphthanone, dibutylphthalate, dicyclohexyl phthalate, isobornyl phthalate and the like,ethyl or butyl naphthenates, and the like, dibutyl sebacate, glycerylsebacate and the like, or the mono alkyl or aryl ethers of glycol, etc.,may be utilized.

In addition, a variety of pigments, extenders or similar materials maybe added to the coating compositions in order to produce in the productuseful and novel effects. In lieu of titanium oxide employed in theexamples, such materials as zinc oxide, barium sulphate, carbon black,chrome yellow, Prussian blue, antimony sulphides, or the like, may beemployed. In lieu of bronze powders other metallic powders or pearlessence, powdered glass or fine sand and the like, may be used. Thesemay be applied to the filaments by being dusted or impinged on thesurface of the coating materials before the surfaces become dry.Additional coating material may then be applied in order to thoroughlycement the adhering substance to the fiber or supporting filament.

In lieu of, or in addition to, the nitrocellulose utilized in Examples 3and 4, other organic cellulose derivatives, e. g., ethyl cellulose,benzyl cellulose, etc., may be employed. In place of, or in addition to,the methyl methacrylate of Example 5. other materials may be used, andas examples of such materials may be mentioned polyacrylic I acid andits esters, polymethacrylic acid and its esters (other than the methylester), polyvinyl derivatives, e. g., the acetate, chloride, andchloroacetate, polyvinyl alcohol, phenol-formaldehyde andurea-formaldehyde resins, etc., ester gum, rosin, etc., casein, gelatin,glue, etc.

The synthetic fibers of the present invention have particularadaptability for employment as artificial bristles in the fabrication ofhair brushes, clothes brushes, tooth brushes, paint brushes, or broomsof various types. Obviously, by obvious modifications coated textilefibers, suitable for use in the manufacture of clothing, stiffenedfabrics, rugs, draperies, table mattings, tapestries, filter cloth, andthe like, may be produced, wherein the treated fiber may be used aloneor interwoven with-other threads or fiber materials. Similarly theymaybe employed as fibers for weaving into coarse cloth of variedcolored. metallic or design effect; as fibers for braiding or twistinginto heavy cord or bundle form; in the manufacture of lamp shades andnovelty products of various kinds; as decorative fiber materials insheaf or tassel form for use in the preparation of artificial flowerdisplays and the like, or for decorative purposes on hats and the like,caps (military uniforms) and the like. Similarly the addition ofpowdered glass or .aluminum powder to a coating material will yieldvaluable fibers adaptable in the fabrication of moving picture screens.

I claim as my invention:

1. A method of producing artificial fibers relatively stiff andresilient in character comprising treating a filamentous material with asolution the essential ingredient of which is acetoneinsoluble cellulosetriacetate containing about 2.7 to about 3 acetyl groups per glucoseunit.

2. A method of producing artificial fibers relatively stiff andresilient in character comprising passing a filament through successivecoating solutions, at least one of which solutions contains as anessential ingredient thereof acetone-insoluble cellulose triacetatecontaining about 2.7 to about 3 acetyl groups per glucose unit.

3. An artificial fiber relatively stiff and resilient in charactercomprising a filamentous core of permeable material having a pluralityof coatings of acetone-insoluble cellulose triacetate containing about2.7 to about 3 acetyl groups per glucose unit.

4. An artificial fiber relatively stiff and resilient in charactercomprising a filamentous base having a coating comprising essentiallyacetone-insoluble cellulose triacetate containing about 2.7 to about 3acetyl groups per glucose unit.

5. An artificial fiber relatively stiff and resilient in charactercomprising a filamentous base having a plurality of coatings appliedthereto, at least one of which coatings comprises essentiallyacetone-insoluble cellulose triacetate containing about 2.7 to about 3acetyl groups per glucose unit.

6. An artificial bristle comprising a viscose rayon filament coated withacetone-insoluble cellulose triacetate containing about 2.7 to about 3acetyl groups per glucose unit.

- MARTIN ELI CUPERY.

